The invention relates to novel siloxane block copolymers having linked, different siloxane blocks and the use thereof.
According to the prior art, there is a large number of surface-active siloxane block copolymers which are used in a wide range of industrial applications. These may be methylpolysiloxanes (cf. DE-C-25 33 074) as well as (pseudo)haloalkyl-substituted siloxanes (cf. DE-C-36 26 297, U.S. Pat. No. 3,952,038 or DE-A-24 02 690), which, for example, are used as cell regulators in highly resilient, cold-curing polyurethane foams. A wide range of silicone-polyether copolymers and their use as surface-active substances are also known, as described, for example, in the following patents by way of example:
DE-C-15 70 647: Chloropolysiloxanyl sulfates are reacted with mixtures of alkylene adducts which consist of
from 50 to 96 OH-equivalent percent of polyalkylene glycol monoethers which consist of ethylene oxide and propylene oxide units and contain from 40 to 70% by weight oxypropylene units and have a molecular weight of from 1000 to 3000, whose hydroxyl groups are preferably secondary, and
from 5 to 50 OH-equivalent percent of alkylene oxide adducts of polyvalent hydroxyl compounds having a molecular weight of from 130 to 3500, whose polyalkylene glycol components consist of ethylene oxide and/or propylene oxide units and have an OH equivalent weight of up to 1750 and whose hydroxyl groups are preferably secondary,
the ratios being chosen so that not more than 1.4, preferably from 1.05 to 1.2, OH equivalents are present per acid equivalent of the chloropolysiloxanyl sulfate.
DE-C-16 94 366: Polysiloxane-polyoxyalkylene block copolymers whose polysiloxane block has a composition known per se but whose polyalkylene block consists of
from 25 to 70% by weight of a polyoxyalkylene having an average molecular weight of from 1600 to 4000 and an ethylene oxide content of from 20 to 100% by weight, the remainder being propylene oxide and optionally higher alkylene oxides, and
from 30 to 75% by weight of a polyoxyalkylene having an average molecular weight of from 400 to 1200 and an ethylene oxide content of from 65 to 100% by weight, the remainder being propylene oxide and optionally higher alkylene oxides,
are used as foam stabilizers.
DE-A-25 41 865: The polysiloxane-polyoxyalkylene block copolymers are defined, with respect to their polyoxyalkylene blocks, in such a way that one polyoxyalkylene block has an average molecular weight of from 900 to 1300 and comprises from 30 to 55% by weight of ethylene oxide, the remainder being propylene oxide, and the other polyoxyalkylene block has an average molecular weight of from 3800 to 5003 and comprises from 30 to 50% by weight of ethylene oxide, the remainder being propylene oxide.
EP-A-0 275 563: The block copolymer described in this patent application comprises three different polyoxyalkylene blocks, namely a block which contains from 20 to 60% by weight of oxyethylene units, with a molecular weight of from 3000 to 5000, a further block having from 20 to 60% by weight of oxyethylene units and a molecular weight of from 800 to 2900 and a third block comprising only polyoxypropylene units and having a molecular weight of from 130 to 1200.
The patent literature furthermore describes siloxane block E-E -copolymers which are used as emulsifiers and in which both polyoxyalkylene groups and long-chain alkyl groups are bonded to linear polysiloxanes (cf. for example U.S. Pat. No. 3,234,252, U.S. Pat. No. 4,047,958 or DE-C-34 36 177).
Further patents (e.g. U.S. Pat. No. 5,136,068, EP-A-0 381 318 and EP-A-0 529 847) describe surface-active siloxane block copolymers for use as emulsifiers, in which polyoxyalkylene radicals and long-chain alkyl radicals are bonded to the polysiloxane and an additional linkage of the siloxane block copolymer via a divalent organic radical is present. The feature of the siloxane block copolymers described is that in all cases identical siloxane blocks are linked to one another by reaction of SiH groups with, for example, diolefins, divinylbenzene or 1,3-divinyltetramethyldisiloxane.
In spite of the large number of siloxane block copolymers thus obtainable, the large number of fields of use for these active substances, for example
as additives for solvent-containing and also low-solvent finishes, surface coatings and pastes,
for coating textiles and paper (tissues),
as starting materials for crosslinking reactions,
as antifoams,
as emulsifiers,
as additives in cosmetic formulations,
as stabilizers for the wide field of PU foam production (on the one hand, a large number of possible polyurethane foam types, such as, for example, flexible foam, rigid foam, ester foam, cold-curing foam, packaging foam, flame-laminatable foam, molding foam, integral foam, etc., and, on the other hand, more modern foaming techniques, such as variable pressure foaming, foaming with inert gases under pressure or forced cooling processes, for example ENVIROxe2x80x94CURE, from CRAIN INDUSTRIES),
makes it necessary to find structures which are further improved.
Surprisingly, it has now been found that the linkage of different siloxane blocks in one molecule has surprising effects in various application tests. According to the teaching of the present invention, different siloxane copolymer blocks (different based on the modifying radicals on the siloxane and/or the structure of the siloxane segment) can be linked to one another in a simple manner via coupling agents, and novel siloxane block copolymers in which the linked siloxane copolymer blocks differ, for example, in their polarities, in their hydrophilic/hydrophobic balance or in proportions of reactive groups can thus be synthesized in a controlled manner.
The present invention thus relates to siloxane block copolymers of the general average formula: 
where the radicals and indices have the following meaning:
A=radical R1, radical E or a radical of the formula IIa 
xe2x80x83or a radical of the formula IIb 
B=radical of the formula IIa or IIb
Y=radical y1 or radical Y2,
D=radical of the formula 
R1=an alkyl radical having 1 to 30 carbon atoms, a substituted alkyl radical, an optionally substituted aryl radical or an optionally substituted alkaryl radical, where however at least 80% of the radicals R1 are methyl groups,
a has a value from 3 to 200,
b has a value from 0 to 50,
c has a value from 0 to 10,
d has a value from 0 to 5 and
e has a value from 0 to 4,
where the values for a, b, c, d and e in the individual segments Z of the radicals A, B and D may be different,
E=radical which
a) is a radical of the general formula
xe2x80x94Rf2xe2x80x94Oxe2x80x94(CmH2mOxe2x80x94)nR3
in which
R2 is a divalent alkyl radical which may also be branched and
f has a value of 0 or 1,
m has a value of, on average, from 2 to 4,
n has a value from 0 to 100 and
R3 is a hydrogen radical, an optionally substituted alkyl radical having 1 to 6 carbon atoms, an acyl radical or a xe2x80x94Oxe2x80x94COxe2x80x94NHxe2x80x94R4 radical in which R4 is an optionally substituted alkyl or aryl radical, and/or
b) has the meaning of an epoxy-functionalized alkyl substituent optionally containing hetero atoms, and/or
c) has the meaning of a mono-, di- and trihydroxyalkyl substituent which may also be aromatic or branched and partially or completely etherified or esterified, and/or
d) has the meaning of a halogen- or pseudohalogen-substituted alkyl, aryl or aralkyl radical which optionally may also be branched,
X=a polyvalent organic radical, with the proviso that at least one radical of the formula IIa or IIb is present in the molecule and at least two of the segments Z are different.
It is also possible to use different substituents in combination, as described, for example, for polyether substituents in DE-C-42 29 402. The substituents may optionally differ from one another, for example in their molar mass, in the case of polyethers possibly in their terminal group R3 or the proportions of the monomers used, in the type of monomers, etc.
X is a polyvalent organic radical (valency=2+e). The radical X is formed by reacting compounds which contain 2+e hydrosilylable olefinic double bonds per molecule with SiH groups. At least one radical X must be present per molecule of compounds according to the invention. The molecule obtained by linkage should contain xe2x89xa6600 Si atoms.
It is clear to a person skilled in the art that the compounds obtained are present in the form of a mixture whose distribution is determined essentially by statistical laws. The values for a, b, c, d and n and the number of X radicals per molecule therefore correspond to average values.
A small proportion of the radicals R1 may be a hydrogen radical, namely when the hydrogensiloxane used does not react completely with the olefinically unsaturated compounds used (e.g. allylpolyethers, xcex1-olefins, allyl glycidyl ethers, etc.) and the organic compounds which form the bridging member X.
X may be, for example, a bridging radical of the formula 
in which
R5 is a divalent alkyl radical which may also be branched and
R6 is a hydrogen radical, an optionally branched alkyl radical or the radical R5 and
g has a value from 0 to 5 and
h has a value from 0 to 4,
or of the formula 
in which R6 has the same meaning as above,
or of the formula 
in which R6 has the same meaning as above,
or of the formula
xe2x80x94R5xe2x80x94Oxe2x80x94(Cmxc2x7H2mxc2x7Oxe2x80x94)nxc2x7R5xe2x80x94
in which
R5 has the same meaning as above,
mxe2x80x2 has a value of, on average, from 2 to 4 and
nxe2x80x2 has a value from 0 to 20,
or of the formula
xe2x80x94R5xe2x80x94(COxe2x80x94)kOCH2xe2x80x94(CR27xe2x80x94)iCH2Oxe2x80x94(COxe2x80x94)kR5xe2x80x94
in which
R5 has the same meaning as above and
R7 is a hydrogen radical, an alkyl radical, a hydroxyalkyl radical or the radical xe2x80x94CH2Oxe2x80x94(COxe2x80x94)kR5xe2x80x94 and
i has a value from 0 to 10 and
k has a value of 0 or 1,
or of the formula 
in which
R8 is an alkyl radical, a substituted alkyl radical, a phenyl radical or the radical R5 and
p has a value from 0 to 10, the value of 0 being preferred, and
if it has the meaning of an alkyl radical, the radical R8 is preferably an alkyl radical having 1 to 6 carbon atoms, particularly preferably a methyl radical,
or of the formula
xe2x80x94R5xe2x80x94NHxe2x80x94COxe2x80x94NHxe2x80x94R5xe2x80x94
in which
R5 has the same meaning as above.
The sum of the R5 radicals per X radical must be 2+e. Preferably, R5 is the radical xe2x80x94(CH2)2xe2x80x94 or xe2x80x94(CH2)3xe2x80x94.
Examples of substances with which the radical X can be formed are 1,7-octadiene, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol triallyl ether, divinylbenzene, divinylcylcohexane, 1,4-butanediol divinyl ether, diallyl polyether, diallylurea and 1,3-divinyltetramethyldisiloxane.
The essential feature of the invention is that, in the average molecule, at least two different siloxane block copolymers are linked to one another. This means that Z in the formula I must differ from that in the formula IIa and/or IIb. This is explained in more detail with reference to the following, schematic formulae: 
The modifying radicals r, s and t have the meaning of the radicals R1 and E. The character of the invention is that either the modifying radical r differs from at least one of the modifying radicals s or t or that the siloxane segment 1 differs from at least one of the other siloxane segments used. Some combinations for the modifying radical r and s, which should be regarded as exemplary, but not limiting, for the scope of the invention, are shown below.
Products in which the modifying radical still contains reactive groups, such as, for example, OH or epoxy groups, are suitable on the one hand for the treatment of surfaces (e.g. fiber preparation, finish additives, etc.) and, on the other hand, for further chemical reactions. Thus, the OH-containing siloxane block copolymers according to the invention can be esterified with methacrylic acid. For example, quats and betaines can be prepared by known processes from the siloxane block copolymers containing epoxy groups.
The respective modifying radical need not be uniform; for example, the modifying radical r may consist of a combination of the radicals r1, r2, r3, etc., which likewise have the meaning of the radicals R1 and E, if it is ensured that either at least one of the modifying radicals further used (s, etc.) has another composition or that at least two different siloxane segments are present.
In general, those compounds which differ by more than 20% in the average number of Si atoms in the individual, linked siloxane blocks or in which the masses of the modifying radicals r, s or t in the individual siloxane segments differ by more than 20% are preferred.
Depending on the desired field of use, various ranges are preferred from the group of compounds claimed:
For applications in the preparation of flexible polyurethane block foams, for example, compounds with b greater than 3 and 5 less than (a+c+d)/b less than 20 are preferred. However, products having an average m in the molecule of 2.3 less than m less than 3.1 are particularly preferred and those having an average m in the molecule of 2.5 less than m less than 2.8 are very particularly preferred.
For use in the preparation of rigid polyurethane foam or polyurethane ester foam, compounds having an average n in the molecule of n less than 28 are preferred, and compounds having an average m in the molecule of m less than 2.5 are particularly preferred. Compounds having an average quotient (a+c+d)/b in the molecule of (a+c+d)/b less than 8 are very particularly preferred.
For applications in the preparation of cold-curing molding foams, compounds having an average b in the molecule of b less than 5 are preferred, and compounds having a total number of radicals E less than 7 are particularly preferred.
For applications in cosmetics or as an emulsifier, compounds in which at least 60% of the radicals R3 are hydrogen radicals or those which contain aromatic substituents in at least one of the modifying radicals used are preferred. Compounds in which at least 80% of the radicals R3 are hydrogen radicals are particularly preferred, and compounds in which all radicals R3 are hydrogen radicals and the average value of m in the molecule is less than 2.3 are very particularly preferred.
For applications as an additive in the field of finishes and surface coatings, those compounds in which at least 80% of the radicals R3 are hydrogen radicals are preferred; and those in which the radical E has the meaning of an epoxy-functionalized alkyl substituent are particularly preferred.